On Sat, 30 Mar 2013 20:45:43 +0000 David Kirkby <david.kir...@onetel.net> wrote:
> Fulll thesis here > http://www.medphys.ucl.ac.uk/research/borl/docs/dkirkby.pdf > > I have seen systems where one sinusoidally modulates the voltage of a > photomultipler tube. You could do the same with an APD. Then it acts a > a mixer. Essentially > > 1) Modulate laser at 100 MHz > 2) Modlulate the APD bias voltage at 100.01 MHz > 3) Detect light from laser on an APD. > 4) Output of the APD is a sine wave at 10 kHz. Thanks! I had a short look at your thesis and i think the idea is not bad. I would need to calculate/simulate what that actually does. > > There has been a similar idea around, using a third laser that > > is pulsed with the desired offset frequency. > > I was wondering if it could be done in more than one stage. A bit like > a superhetrodyne receiver. Probably. But as steep filters for optics are kind of hard to come by, i think a super heterodyne design isn't realy going to work. But probably using an APD with gain modulation at 1GHz or so, i could down modulate the signal to something that is easier to handle (ie something similar as a direct conversion software defined radios). I wonder if this would work with normal PIN photodiodes as well, as their price is much lower than APDs. Attila Kinali -- The people on 4chan are like brilliant psychologists who also happen to be insane and gross. -- unknown _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
